“Non-contact ultrasonic resonant spectroscopy resolves the elastic properties of layered plant tissues,” was published online on the 21 December 2018, in Applied Physics Letters (Vol.113, Issue 25).
We have been able, for the first time, to resolve in a quantitative way, in vivo and using ultrasound, the layered structure of subwavelength layers in complex layered layered tissues.
We obtained, for the firt time, the elastic modulii of the pallisade parenchyma and the spongy mesophyl that present a very large anisotropy, as it was expected from SEM micrographs and the available knowledge about these tissues.
The key features for these results are:
(1) use of high sensitivity and very wide band air-coupled ultrasonic trasducers (0.1 – 1.2 MHz) to measure several orders of the thickness resonances and the frequency range where the resonances are completely damped out using a non-contact technique
(2) Identification of a species that permits to obtain samples with controlled and limited differences, this permits to confirm the obtained results and observed trends.
(3) The implementation of a Simulated Annealing algorithm that permits to solve the inverse problem even in the case of layered tissues where the number of unknowns (dimension of the space of seach) is very large (8).